1. Field of the Invention
This invention relates to disk drive suspensions, and more particularly to the manufacture of multilayer gimbal suspension elements for suspensions using fewer process steps through simultaneous etching of multiple layers heretofore etched separately.
2. Description of the Related Art
Some disk drive suspension wireless gimbal suspension elements convey electrical signals between the recording head and the associated external circuitry, and also provide a mechanical flexure function. There are two main configurations of these gimbal suspension elements. Both configurations are multilayer and typically comprise a stainless steel-polyimide-copper laminate. In one type, an initial laminate is progressively reduced to the gimbal suspension element, commonly referred to as the “subtractive” type, e.g. TSA and ILS. In the second type, generally referred to as the additive type, e.g. CIS, the laminate is built up using as the base a stainless steel foil and adding polyimide, and the adding to the polyimide metal conductive layers through sputtering or plating techniques.
The present processes for fabrication of these gimbal suspension elements involve process steps which expose the constituent materials to harsh chemicals and severe environments. The highly acidic or basic solutions used can degrade the bond interfaces between the assembled dissimilar materials. Highly accelerated stress tests have been developed to accelerate the impact of these environmental exposures upon the suspension components. The pressure cooker test subjects to 121° C., 2 Atm. pressure, and 100% relative humidity (RH) for 168 hours. Use adhesion promoting layers has been shown to perform effectively in these tests.
Etching of these adhesion promoting layers in processing must be carried out as a separate step since their solubility is different from the other laminate layers, such as the copper seed layer usually used. An etching of chromium adhesion layers can result in the presence of hexavalent chromium in the effluent, an environmentally hazardous and unacceptable course.